|Scientific Name:||Eumetopias jubatus ssp. monteriensis|
|Species Authority:||(Schreber, 1776)|
|Taxonomic Notes:||In previous IUCN evaluations, Steller Sea Lions have been treated as a single species. The species was listed as two separate stocks (officially called “distinct population segments”) under the United States Endangered Species Act (ESA) in 1997 based on the phylogeographic method (Loughlin 1997). Since that time, the stocks have been listed as endangered west of 144° W latitude, and threatened east of 144° W. Although the strongest evidence for stock separation at the time was the distribution of mtDNA haplotypes across the range, a divergence in population trend was also apparent. The two stocks have continued to display diverging trends, with continued increases in the east for at least 30 years and stability or slight increases in the west with localized areas of decline. In 2009, C. Phillips and co-authors (Phillips et al. 2009) published a manuscript that argued for sub-species designation for the two stocks based on morphological and genetic studies. The Society for Marine Mammalogy Ad-Hoc Committee on Taxonomy subsequently recognized two subspecies of Eumetopias jubatus, E. j. jubatus and E. j. monteriensis (Committee on Taxonomy 2012).|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||Gelatt, T. & Lowry, L.|
|Reviewer/s:||Kovacs, K.M. & Burkanov, V.|
Eumetopias jubatus monteriensis has shown a steady increase in abundance (at an average growth rate of 4.3% (95% CL 1.9% – 7.3%) per year) for more than 30 years which is equivalent to three generations with new rookeries being established in southeast Alaska. The existing population is estimated to include about 65,000 animals. There are no threats currently limiting this population, and continued growth is anticipated until density dependent factors take effect. Therefore, E. j. monteriensis qualifies for listing by IUCN as Least Concern. The agency responsible for management of Steller Sea Lions in the United States, the National Marine Fisheries Service (NMFS), drafted a species status review which recommended that the eastern subspecies should be removed from the ESA threatened and endangered species list (NMFS 2012).
|Range Description:||Loughlin’s Northern Sea Lions (commonly described as the eastern distinct population segment of the Steller Sea Lion; NMFS 2008) normally occur from central California, north along the west coast of North America to Cape Suckling, Alaska at 144° W latitude (NMFS 2012). Eumetopias jubatus monteriensis breeds as far south as Año Nuevo Island in Central California.|
Native:Canada (British Columbia); United States (Alaska, Aleutian Is., California, Oregon, Washington)
|FAO Marine Fishing Areas:||
Pacific – eastern central; Pacific – northeast
|Range Map:||Click here to open the map viewer and explore range.|
The Loughlin’s Northern Sea Lion population was estimated to number between 58,334 and 72,223 in 2009 (NMFS 2012). The most recent (2011) best estimate is 65,000 (NMFS unpublished data). Abundance declined in the 1950s and 1960s due to government sanctioned culling in British Columbia and Alaska. In the early 1970s laws were enacted to protect the species, and abundance has increased since then. Over the past three generations (30 years), abundance of E. j. monteriensis has increased by 170%, this increase is in marked contrast to the situation with western Steller Sea Lions that declined severely between1960 and 2000.
The majority of the breeding population is in the northern portion of the range with approximately 52% of the population in Southeast Alaska and 32% in British Columbia. Oregon (6%) and California (10%) contain the remainder of the population.
A population viability analysis of Loughlin’s Northern Sea Lions was conducted as part of the 2008 Steller Sea Lion Recovery Plan (NMFS 2008). Based on an increasing trend and the elimination of the primary threat to the taxon (U.S. and Canadian government-sanctioned culling) the probability of quasi-extinction of this population within 100 years is less than 10%.
|Habitat and Ecology:||
Eumetopias jubatus are the largest otariids and the fourth largest pinniped. Both sexes are robust and powerfully built. They are sexually dimorphic, with adult males weighing three times as much, and growing 20–25% longer than, adult females. Pups are born with a thick blackish-brown lanugo that is moulted by about six months of age. The maximum length of adult males is about 3.3 m and average weight is 1,000 kg. The maximum length for adult females is about 2.5 m and average weight is 273 kg. Pups are born at an average size of about 1 m and 18–22 kg (Loughlin 2009).
The greatest threat to Loughlin’s Northern Sea Lions has been intentional culling in Southeast Alaska and Canada in the 1950s and 1960s. Those practices were discontinued in the early 1970s and the population has been increasing ever since. Some are killed in nets in fisheries off the west coast of North America. An unknown number may be shot during commercial fishing operations although it is generally believed that this source of mortality has been reduced dramatically since the establishment of federal laws prohibiting killing of sea lions in Canada and the United States (NMFS 2012). The 2008 Steller Sea Lion Recovery Plan found that there were no apparent threats limiting the recovery of this population, and the increasing population trend confirms that conclusion (NMFS 2008).
Loughlin’s Northern Sea Lions are protected in the United States and Canada. In the U.S. they are listed as depleted under the Marine Mammal Protection Act. The entire species (E. jubatus) was listed as threatened under the ESA in 1990, and in 1997 the western population (corresponding to E. j. jubatus) was uplisted to endangered. A recovery plan for Steller Sea Lions was approved in 1992, and a revised recovery plan was published in 2008. Critical habitat was designated in 1993, including no entry zones near rookeries and management of fisheries activity in the vicinity of rookeries. Substantial funding has been made available for Steller Sea Lion research to develop information on ecology, behaviour, genetics, population dynamics, and movements. Results have been used to assist in the development of management activities, to attempt to understand the reasons for the decline of the western Steller Sea Lion, and to promote recovery of the species (NMFS 2008). In 2012, the agency responsible for management of sea lions in the U. S., the National Marine Fisheries Service, drafted a species status review which concluded that Loughlin’s Northern Sea Lions should be removed from the ESA threatened and endangered species list (NMFS 2012).
Calkins, D. G. and Pitcher, K. W. 1982. Population assessment ecology and trophic relationships of Steller’s sea lions in the Gulf of Alaska. Environmental assessment of the Alaskan Continental shelf. U.S. Dept. of Commerce and U.S. Dept. of Interior, Final Reports of Principal Investigators, pp. 447-546.
Committee on Taxonomy. 2012. List of marine mammal species and subspecies. Available at: www.marinemammalscience.org. (Accessed: 7 May 2012.).
IUCN. 2012. IUCN Red List of Threatened Species (ver. 2012.2). Available at: http://www.iucnredlist.org. (Accessed: 17 October 2012).
Loughlin, T.R. 1997. Using the phylogeographic method to identify Steller sea lion stocks. In: A. Dizon, S.J. Chivers and W.F. Perrin (eds), Molecular Genetics of Marine Mammals, pp. 159–171. Society for Marine Mammalogy Special Publication 3, Lawrence, Kansas, USA.
Loughlin, T.R. 2009. Steller sea lion Eumetopias jubatus. In: W.F. Perrin, B. Wursig and J.G.M. Thewissen (eds), Encyclopedia of Marine Mammals, pp. 1107-1110. Academic Press.
Loughlin, T.R., Sterling, J.T., Merrick, R.L., Sease, J.L. and York, A.E. 2003. Immature Steller sea lion diving behavior. Fishery Bulletin 101: 566-582.
National Marine Fisheries Service. 2008. Recovery Plan for the Steller Sea Lion (Eumetopias jubatus). Revision. National Marine Fisheries Service, Silver Spring, Maryland, USA.
National Marine Fisheries Service. 2012. Draft Status Review of The Eastern Distinct Population Segment of Steller Sea Lion (Eumetopias jubatus). National Marine Fisheries Service, Juneau, Alaska, USA.
Phillips, C.D., Bickham, J.W., Patton, J.C. and Gelatt, T.S. 2009. Systematics of Steller sea lions (Eumetopias jubatus): subspecies recognition based on concordance of genetics and morphometrics. Occasional Papers, Museum of Texas Tech University 283: 1-15.
Pitcher, K.W., Calkins, D.G. and Pendleton, G.W. 1998. Reproductive performance of female Steller sea lions: an energetics-based reproductive strategy? Canadian Journal of Zoology 76: 2075-2083.
Rehberg, M.J. and Burns, J.M. 2008. Differences in diving and swimming behavior of pup and juvenile Steller sea lions (Eumetopias jubatus) in Alaska. Canadian Journal of Zoology 86: 539-553.
Trites, A. W., Calkins, D. G. and Winship, A. J. 2007. Diets of Steller sea lions (Eumetopias jubatus) in Southeast Alaska, 1993-1999. Fishery Bulletin 105: 234-248.
|Citation:||Gelatt, T. & Lowry, L. 2012. Eumetopias jubatus ssp. monteriensis. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 19 June 2013.|
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